Malaysia Airlines Flight MH17 suffered a “massive explosive decompression” when shrapnel from a surface-to-air missile ripped through the Boeing 777 over eastern Ukraine, according to data from the “black box” recorders revealed on Monday.

The news came as Ukrainian soldiers finally seized part of the vast site where the plane crashed July 17.

Fighting near the crash site had delayed a team of international investigators from reaching and securing the wreckage for a second straight day. Bodies and crucial evidence have been lying at the site for almost two weeks.

“It’s absolutely unconscionable that they remain out there,” said Michael Bociurkiw, a spokesman for monitors from the Organization for Security and Cooperation in Europe, in rebel-held Donetsk.

Alexander Hug, the deputy head of OSCE, said the team, made up of Dutch and Australian police, hoped to have access to the site Tuesday.

“There is a job to be done,” he said. “We have made it clear to everyone involved that tomorrow we absolutely have to have safe access.”

Ukrainian officials blamed the violence that had been preventing the team from completing its mission on the pro-Russian separatists, who they say are trying to stall as they continue to manipulate the scene in an effort to “wipe out any sort of traces” of their involvement in the attack, according to Ukrainian Foreign Minister Pavlo Klimkin.

Separatist officials have staunchly denied responsibility for shooting down the airliner, which killed all 298 people on board.

Meanwhile, the Ukrainian government continued its bloody campaign to try to regain control of territories in the eastern part of the country that had been lost to rebel forces in recent days around Donetsk, including the area around where MH17 crashed.

The mandate of the police team is to secure the currently rebel-controlled area so that comprehensive investigations can begin and any remaining bodies can be recovered.